Stereoscopic 3D liquid crystal display with segmented light guide

ABSTRACT

A backlight for a stereoscopic 3D liquid crystal display apparatus includes a light guide formed from a plurality of segments. Each segment has a first side and a second side opposite the first side, and a first surface extending between the first and second sides and a second surface opposite the first surface. The first surface substantially re-directs light and the second surface substantially transmits light. The plurality of segments are arranged substantially in parallel with the second surfaces transmitting light in substantially the same direction to provide backlighting for a stereoscopic 3D liquid crystal display. A light source is disposed along only one of the first side or second side of each segment for transmitting light into the light guide from either the first side or second side. Each segment light source is selectively turned on and off in a particular pattern.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 60/828,399 filed Oct. 6, 2006.

FIELD

The present disclosure relates to a backlit liquid crystal displayapparatus and particularly to displaying stereo 3D images using a liquidcrystal display with a segmented light guide.

BACKGROUND

A stereoscopic 3D display usually presents an observer with images withparallax from individual right and left eye viewpoints. There are twomethods of providing the two eyes of the observer with the parallaximages in a time sequential manner. In one method, the observer utilizesa pair of shutter or 3D glasses which transmit or block light from theviewer's eyes in synchronization with alternating the left/right imagedisplay. Similarly, in another method, right eye and left eye viewpointsare alternatively displayed and presented to the respective eyes of theobserver but without the use of 3D glasses. This second method isreferred to as autostereoscopic and is sometimes desirable for stereo 3Dviewing because separate glasses are not needed though there is limitedpermissible head motion.

A liquid crystal display (LCD) is a sample and hold display device suchthat the image at any point or pixel of the display is stable until thatpixel is updated at the next image refresh time, typically 1/60 of asecond or faster. In such a sample and hold system, displaying differentimages, specifically displaying alternating left and right images for anautostereoscopic display, requires careful timing sequencing of thelight sources so that, for example, the left eye image light source isnot on during the display of data for the right eye and vice versa.

Turning on the light source to light the first or right image at timet=0 provides light to the right image. At time t=16.67 ms (typical 60 Hzrefresh rate) the second or left image starts to be put in place. Thesecond image replaces the first image and can take 16.67 ms to completethe transformation. Current systems turn off all the light sources thatilluminate the first or right image and then turn on all the lightsources that illuminate the second or left image at sometime during thesecond image transformation. This can lead to “cross-talk” or “ghosting”of the first or right image in the second or left image, degrading thestereoscopic 3D effect. An additional source of crosstalk in currentsystems is light reflection from a left or right source off of theopposite source window backwards toward the original source.

BRIEF SUMMARY

The present disclosure relates to a backlit liquid crystal displayapparatus and particularly to displaying stereo 3D images using a liquidcrystal display with a segmented light guide.

In a first embodiment, a backlight for a stereoscopic 3D liquid crystaldisplay apparatus includes a light guide formed from a plurality ofsegments. Each segment has a first side and a second side opposite thefirst side, and a first surface extending between the first and secondsides and a second surface opposite the first surface. The first surfacesubstantially re-directs light and the second surface substantiallytransmits light. The plurality of segments are arranged substantially inparallel with the second surfaces transmitting light in substantiallythe same direction to provide backlighting for a stereoscopic 3D liquidcrystal display. A light source is disposed along only one of the firstside or second side of each segment for transmitting light into thelight guide from either the first side or second side. Each segmentlight source is selectively turned on and off in a particular pattern.

In another embodiment, a stereoscopic 3D liquid crystal displayapparatus includes a liquid crystal display panel, drive electronicsconfigured to drive the liquid crystal display panel with alternatingleft eye and right eye images, and a backlight positioned to providelight to the liquid crystal display panel. The backlight includes alight guide formed from a plurality of segments. Each segment has afirst side and a second side opposite the first side, and a firstsurface extending between the first and second sides and a secondsurface opposite the first surface. The first surface substantiallyre-directs light and the second surface substantially transmits light.The plurality of segments are arranged substantially in parallel withthe second surfaces transmitting light in substantially the samedirection to provide backlighting for a stereoscopic 3D liquid crystaldisplay. A light source is disposed along only one of the first side orsecond side of each segment for transmitting light into the light guidefrom either the first side or second side. Each segment light source isselectively turned on and off in a particular pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIG. 1 is a schematic side view of an illustrative display apparatus;

FIG. 2A and FIG. 2B are schematic side views of an illustrative displayapparatus in operation; and

FIG. 3A is a schematic diagram front view of an illustrative backlightfor displaying alternating right and left images;

FIG. 3B is a side elevation view of the illustrative backlight of FIG.3A;

FIG. 4 is a schematic diagram front view of another illustrativebacklight for displaying alternating right and left images; and

FIG. 5 is a schematic side elevation view of another illustrativebacklight for displaying alternating right and left images.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which are shown by way ofillustration several specific embodiments. It is to be understood thatother embodiments are contemplated and may be made without departingfrom the scope or spirit of the present invention. The followingdetailed description, therefore, is not to be taken in a limiting sense.

All scientific and technical terms used herein have meanings commonlyused in the art unless otherwise specified. The definitions providedherein are to facilitate understanding of certain terms used frequentlyherein and are not meant to limit the scope of the present disclosure.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein.

The recitation of numerical ranges by endpoints includes all numberssubsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3,3.80, 4, and 5) and any range within that range.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” encompass embodiments having pluralreferents, unless the content clearly dictates otherwise. As used inthis specification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

The term “autostereoscopic” refers to displaying three-dimensionalimages that can be viewed without the use of special headgear or glasseson the part of the user or viewer. These methods produce depthperception for the viewer even though the image is produced by a flatdevice. The term stereoscopic 3D incorporates the field ofautostereoscopic devices but also includes the stereoscopic 3D displaycase in which special headgear, typically shutter glasses, are need tosee stereoscopic 3D from a flat device.

The present disclosure relates to a backlit liquid crystal displayapparatus and particularly to displaying stereo 3D images using a liquidcrystal display with a segmented light guide. This apparatus can providea spatially controlled, variable intensity light source formed fromhorizontally arranged zones of light. In many embodiments, thesesegmented backlights utilize segments of channels that are interleaved,where adjacent segment or channel pairs are lit from opposite sides ofthe light guide. These segments or channels are arranged such thatadjacent segment or channel segments have an alternating right and leftlight directionality.

Ghosting is created when all or a portion of the LCD panel has not beencompletely erased of the previous image and the directional backlight isswitched. For example, if the left image is displayed with the leftimage light source, ghosting will occur if the right image light sourceis turned on before the display is either made black or the right imagebecomes stable on the display.

This segmented backlight provides alternating right and left lightdirectionality for adjacent backlight channels or segments, reducesimage “cross-talk” or image “ghosting” in autostereoscopic 3D displays.These segmented light guides can thus be designed to extract most if notnearly all of the light from the light guide with a single pass througheach channel or segment. Light emitting diodes can be utilized at asingle end of each channel or segment to illuminate the edge of thethin, narrow channel or segment of a light guide. In some embodiments,time sequencing each horizontal zone (plurality of adjacent segments)can provide a scanning backlight solution. In these embodiments, thezones of the light guide can have a width that is sized relative to theLCD panel response time to that the entire backlight, are completely litwithin one display refresh. In some embodiments, one or more zones aresequentially lit in synchronization with the display.

One or more of these embodiments may be combined in a single displaycapable of providing a 3D visualization capability from a flat displayeither in a shutter glasses stereoscopic 3D display mode or in anautostereoscopic display mode. While the present invention is not solimited, an appreciation of various aspects of the invention will begained through a discussion of the examples provided below.

A liquid crystal display is a sample and hold display device such thatthe image at any particular point is stable until that point or pixel isupdated at the next image refresh time, typically within 1/60 of asecond or faster. In such a sample and hold system, displaying differentimages, specifically alternating left and right images for a 3D display,during sequential refresh periods of the display requires carefulsequencing of the backlight light sources so that, for example, the lefteye light source is not on during the display of data for the right eyeand vice versa.

FIG. 1 is a schematic side view of an illustrative display apparatus 10.The display apparatus includes a liquid crystal display panel 20 and abacklight 30 positioned to provide light to the liquid crystal displaypanel 20. The backlight 30 includes a right eye image solid state lightsource 32 or plurality of first light sources 32, and a left eye imagesolid state light source 34 or plurality of second light sources 34,capable of being modulated between the right eye image solid state lightsource 32 and the left eye image solid state light source 34 at a rateof, in many embodiments, at least 90 Hertz. A double sided prism film 40is disposed between the liquid crystal display panel 20 and thebacklight 30.

The liquid crystal display panel 20 and/or backlight 30 can have anyuseful shape or configuration. In many embodiments, the liquid crystaldisplay panel 20 and backlight 30 has a square or rectangular shape.However, in some embodiments, the liquid crystal display panel 20 and/orbacklight 30 has more than four sides or is a curved shape. While thepresent disclosure is directed to any stereoscopic 3D backlightincluding those requiring shutter glasses or more than a singlelightguide and associated liquid crystal display panel, the presentdisclosure is particularly useful for autostereoscopic displays.

A synchronization driving element 50 is electrically connected to thebacklight 30 plurality of first and second light sources 32, 34 and theliquid crystal display panel 20. The synchronization driving element 50synchronizes activation and deactivation (i.e., modulation) of the righteye image solid state light source 32 and the left eye image solid statelight source 34 as image frames are provided at a rate of, in manyembodiments, 90 frames per second or greater to the liquid crystaldisplay panel 20 to produce a flicker-free still image sequence, videostream or rendered computer graphics. An image (e.g., video or computerrendered graphics) source 60 is connected to the synchronization drivingelement 50 and provides the images frames (e.g., right eye images andleft eye images) to the liquid crystal display panel 20.

The liquid crystal display panel 20 can be any useful transmissiveliquid crystal display panel. In many embodiments, liquid crystaldisplay panel 20 has a frame response time of less than 16 milliseconds,or less than 10 milliseconds, or less than 5 milliseconds. Commerciallyavailable transmissive liquid crystal display panels having a frameresponse time of less than 10 milliseconds, or less than 5 milliseconds,or less than 3 milliseconds, are for example Toshiba MatsushitaDisplay's (TMD) optically compensated bend (OCB) mode panel LTA090A220F(Toshiba Matsushita Display Technology Co., Ltd., Japan).

The backlight 30 can be any useful backlight that can be modulatedbetween a right eye image solid state light source 32 and left eye imagesolid state light source 34 at a rate of, in many embodiments, at least90 Hertz, or 100 Hertz, or 110 Hertz, or 120 Hertz, or greater than 120Hertz.

The illustrated backlight 30 includes a first side 31 or first lightinput surface 31 adjacent to the plurality of first light sources 32 orright eye image solid state light source 32 and an opposing second side33 or second light input surface 33 adjacent to the plurality of secondlight sources 34 or left eye image solid state light source 34. A firstsurface 36 extends between the first side 31 and second side 33, and asecond surface 35, opposite the first surface 36, extends between thefirst side 31 and second side 33. The first surface 36 substantiallyre-directs (e.g., reflects, extracts, and the like) light and the secondsurface 35 substantially transmits light. In many embodiments, a highlyreflective surface is on or adjacent to the first surface 36 to assistin re-directing light out through the second surface 35.

In many embodiments, the first surface 36 includes a plurality ofextraction elements such as, for example, linear prism or lenticularfeatures as shown. In many embodiments, the linear prism or lenticularfeatures can extend in a direction parallel to the first side 31 andsecond side 33 or parallel to the linear prism and lenticular featuresof the double sided prism film 40.

The solid state light sources can be any useful solid state light sourcethat can be modulated at a rate of, for example, at least 90 Hertz. Inmany embodiments, the solid state light source is a plurality of lightemitting diodes such as, for example, Nichia NSSW020B (Nichia ChemicalIndustries, Ltd., Japan). In other embodiments, the solid state lightsource is a plurality of laser diodes or organic light emitting diodes(i.e., OLEDs). The solid state light sources can emit any number ofvisible light wavelengths such as red, blue, and/or green, or range orcombinations of wavelengths to produce, for example, white light. Thebacklight can be a single layer of optically clear material with lightsources at both ends or two (or more) layers of optically clear materialwith a light source per layer which preferentially extract light in adesired direction for each layer.

The double sided prism film 40 can be any useful prism film having alinear lenticular structure on a first side and a linear prismaticstructure on an opposing side. The linear lenticular structure and thelinear prism structure are parallel. The double sided prism film 40transmits light from the scanning backlight to the liquid crystaldisplay panel 20 at the proper angles such that a viewer perceives depthin the displayed image. Useful, double sided prism films are describedin United States Patent Publication Nos. 2005/0052750 and 2005/0276071,which are incorporated herein to the extent they do not conflict withthe present disclosure.

The image source 60 can be any useful image source capable of providingimages frames (e.g., right eye images and left eye images) such as, forexample, a video source or a computer rendered graphic source. In manyembodiments, the video source can provide image frames from 50 to 60Hertz or greater. In many embodiments, the computer rendered graphicsource can provide image frames from 100 to 120 Hertz or greater.

The computer rendered graphic source can provide gaming content, medicalimaging content, computer aided design content, and the like. Thecomputer rendered graphic source can include a graphics processing unitsuch as, for example, an Nvidia FX5200 graphics card, a Nvidia GeForce9750 GTX graphics card or, for mobile solutions such as laptopcomputers, an Nvidia GeForce GO 7900 GS graphics card. The computerrendered graphic source can also incorporate appropriate stereo driversoftware such as, for example, OpenGL, DirectX, or Nvidia proprietary 3Dstereo drivers.

The video source can provide video content. The video source can includea graphics processing unit such as, for example, an Nvidia Quadro FX1400graphics card. The video source can also incorporate appropriate stereodriver software such as, for example, OpenGL, DirectX, or Nvidiaproprietary 3D stereo drivers.

The synchronization driving element 50 can include any useful drivingelement providing synchronizing activation and deactivation (i.e.,modulation) of the right eye image solid state light source 32 and theleft eye image solid state light source 34 with image frames provided ata rate of, for example, 90 frames per second or greater to the liquidcrystal display panel 20 to produce a flicker-free video or renderedcomputer graphics. The synchronization driving element 50 can include avideo interface such as, for example, a Westar VP-7 video adaptor(Westar Display Technologies, Inc., St. Charles, Mo.) coupled to customsolid state light source drive electronics.

FIG. 2A and FIG. 2B are schematic side views of an illustrative displayapparatus 10 in operation. In FIG. 2A the left eye image solid statelight source 34 (i.e., plurality of second light sources 34) isilluminated and the right eye image solid state light source 32 (i.e.,plurality of first light sources 32) is not illuminated. In this state,the light emitted from the left eye image solid state light source 34transmits through the backlight 30, through the double sided prism sheet40, and liquid crystal panel 20 providing a left eye image directedtoward the left eye 1 a of an viewer or observer. In FIG. 2B the righteye image solid state light source 32 is illuminated and the left eyeimage solid state light source 34 is not illuminated. In this state, thelight emitted from the right eye solid state light source 32 transmitsthrough the backlight 30, through the double sided prism sheet 40, andliquid crystal panel 20 providing a right eye image directed toward theright eye 1 b of an viewer or observer. It is understood that while theright eye solid state light source 32 is located on the right side ofthe light guide and the left eye image solid state light source 34 islocated on the left side of the light guide, is some embodiments, theright eye solid state light source 32 is located on the left side of thelight guide and the left eye image solid state light source 34 islocated on the right side of the light guide.

The light sources 32, 34 can be air coupled or index matched to thebacklight light guide. For example, a packaged light source device(e.g., LED) can be edge-coupled without index matching material into thelight guide. Alternatively, packaged or bare die LEDs can be indexmatched and/or encapsulated in the edge of the light guide for increasedefficiency. This feature may include additional optical features, e.g.,injection wedge shapes, on the ends of the light guide to efficientlytransport the input light. The LEDs can be alternatively embedded in theedge or side 31, 33 of the light guide with appropriate features toefficiently collect and collimate the LED light into TIR (i.e., totalinternal reflection) modes of the light guide.

Liquid crystal display panels 20 have a refresh or image update ratethat is variable, but for the purposes of this example, a 60 Hz refreshrate is presumed. This means that a new image is presented to the viewerevery 1/60 second or 16.67 milliseconds (msec). In the 3D system thismeans that at time t=0 (zero) the right image of frame one is presented.At time t=16.67 msec the left image of frame one is presented. At timet=2*16.67 msec the right image of frame two is presented. At timet=3*16.67 msec the left image of frame two is presented, and thisprocess is thus repeated. The effective frame rate is half that of anormal imaging system because for each image a left eye and right eyeview of that image is presented.

In this example, turning the first plurality of light sources on tolight the right (or left) image at time t=0 provides light to the right(or left) image, respectively. At time t=16.67 msec the second imageleft or right, starts to be put in place. This image replaces the “timet=0 image” from the top of the LCD panel to the bottom of the LCD, whichtakes 16.67 msec to complete in this example. Non-scanned solutions turnoff all the first plurality of light sources and then turns on all thesecond plurality of light sources sometime during this transition.

Providing at least 45 left eye images and at least 45 right eye images(alternating between right eye and left eye images and the images arepossibly a repeat of the previous image pair) to a viewer per secondprovides a flicker-free 3D image to the viewer. Accordingly, displayingdifferent right and left viewpoint image pairs from computer renderedimages or images acquired from still image cameras or video imagecameras, when displayed in synchronization with the switching of thelight sources 32 and 34, enables the viewer to visually fuse the twodifferent images, creating the perception of depth from the flat paneldisplay. A limitation of this visually flicker-free operation is that,as discussed above, the backlight should not be on until the new imagethat is being displayed on the liquid crystal display panel hasstabilized; otherwise cross-talk and a poor stereoscopic image will beperceived.

The segmented backlight 30 and associated light sources 32, 34 describedherein can be very thin (thickness or diameter) such as, for example,less then 5 millimeters, or from 0.25 to 5 millimeters, or from 0.5 to 4millimeters, or from 0.5 to 2 millimeters.

FIG. 3A is a schematic diagram front view of an illustrative backlight30 for displaying alternating right and left images. FIG. 3B is a sideelevation view of the illustrative backlight of FIG. 3A. The backlight30 is formed from a plurality of segments 30 ₁, 30 ₂, 30 ₃, 30 ₄, 30 ₅,and 30 ₆. First side light input segments 30 ₂, 30 ₄, 30 ₆ and secondside light input segments 30 ₁, 30 ₃, 30 ₅ are interleaved such thatadjacent segments 30 ₁, 30 ₂, 30 ₃, 30 ₄, 30 ₅, and 30 ₆ alternatebetween first side light input segments 30 ₂, 30 ₄, 30 ₆ and second sidelight input segments 30 ₁, 30 ₃, 30 ₅. Thus, the backlight 30 providesright eye image view light and left eye image view light in separateadjacent segments. This de-coupled light right eye image view light andleft eye image view light allows the segments to be designed tospecifically transmit all or nearly all the light out of the segment, asopposed to each segment designed to transmit light both right eye imageview light and left eye image view light.

Each first side light input segment 30 ₂, 30 ₄, 30 ₆ includes a firstside 31 or first light input surface 31 adjacent to the plurality offirst light sources 32 ₂, 32 ₄, 32 ₆ or right eye image solid statelight source 32 ₂, 32 ₄, 32 ₆ and an opposing second side 33. Eachsecond side light input segment 30 ₁, 30 ₃, 30 ₅ includes a second lightinput surface 33 adjacent to the plurality of second light sources 34 ₁,34 ₃, 34 ₅ or left eye image solid state light source 34 ₁, 34 ₃, 34 ₅.A first surface (36 ₆ for example and also shown in FIG. 1 referencenumber 36) extends between the first side 31 and second side 33 and asecond surface 35 ₁, 35 ₂, 35 ₃, 35 ₄, 35 ₅, 35 ₆, opposite the firstsurface (36 ₆ for example), extends between the first side 31 and secondside 33. The first surface (36 ₆ for example) substantially re-directs(e.g., reflects, extracts, and the like) light and the second surface 34₁, 34 ₂, 34 ₃, 34 ₄, 34 ₅, 34 ₆ substantially transmits light to thedouble sided prism film and LCD panel, as described in FIG. 1.

Each segment 30 ₁, 30 ₂, 30 ₃, 30 ₄, 30 ₅, 30 ₆ can be separated fromeach other with a gap 37, such as an air gap 37, for example. The gaps37 can be formed by cutting or otherwise making gaps 37 that separate atleast a portion of each segment thickness from an adjacent segment.These gaps 37 can be air gaps that at least partially optically separateadjacent segments from each other. These gaps 37 can be optical gapsthat, for example, can be physical gaps filled with a material with adifferent index of refraction and/or absorption or scattering ascompared to the bulk material of the light guide. As illustrated, thesegments remained joined at the edges of the light guide to stiffen andsupport the segments structures.

FIG. 3B illustrates segments that are partially separated by an air gap37 and partially joined to each other at the second surface. However, itis understood that the segments can be alternatively joined at the firstsurface, not shown. In other embodiments, segments are partiallyseparated by an air gap 37 at both the second surface and the firstsurface, and partially joined to each other between the second surfaceand the first surface. In embodiments where the segments are partiallyjoined to an adjacent segment, the joining thickness can be any usefulpercentage of the total thickness of the segments. In many embodiments,the joining thickness is a value in a range from 1 to 90% or from 1 to50% or from 1 to 25%.

While six channels or segments 30 ₁, 30 ₂, 30 ₃, 30 ₄, 30 ₅, 30 ₆ areshown, it is understood that any useful number of channel or segments 30₁, 30 ₂, 30 ₃, 30 ₄, 30 ₅, 30 ₆ can be utilized to form the backlight30.

Each segment 30 ₁, 30 ₂, 30 ₃, 30 ₄, 30 ₅, 30 ₆ includes a light sourceon only one side 31 or 33 of each segment 30 ₁, 30 ₂, 30 ₃, 30 ₄, 30 ₅,30 ₆. In many embodiments, adjacent segment 30 ₁, 30 ₂, 30 ₃, 30 ₄, 30₅, 30 ₆ pairs have the light source 32 or 34 opposing sides 31 or 33 ofeach segment 30 ₁, 30 ₂, 30 ₃, 30 ₄, 30 ₅, 30 ₆. This configuration“de-couples” right eye image and left eye image light source from eachother and assists in reducing image “cross-talk” or image “ghosting” ona 3D display.

The backlight can be formed by placing each segment next to each otherand adhering the segments together or fixed in a parallel manner withall the second surfaces transmitting light in substantially the samedirection to provide backlighting for the stereoscopic 3D liquid crystaldisplay.

Thus, each segment includes a light source transmitting light into onlyone side of each segment, a light transmission surface and an opposinglight re-directing surface extending between the segment first side andsegment second side. The plurality of segments are arrangedsubstantially in parallel and with the first surfaces transmitting lightin substantially the same direction to provide backlighting for astereoscopic 3D liquid crystal display. In many embodiments, the videoor data signals drive the LCD panel in synchronization with sequentiallighting of the segments or groups of segments down the display.

In many embodiments, the backlight 30 right eye image view segments orgroups of adjacent segments are lit (by only one side) sequentially fromthe top of the display to the bottom of the display for a first image(e.g., a right eye view image) and then the backlight 30 left eye viewsegments or groups of adjacent segments are lit (by only one side)sequentially from the top of the display to the bottom of the displayfor a second image from (e.g., a left eye view image). A rolling segmentcan be unlit from either side to separate the right eye view image fromthe left eye view image.

Various mechanical support methods may be used to maintain the parallelalignment of the segments. A backing film, possibly with lightextraction features and a highly reflective surface can be laminated tothe segments. The backing material of thin metal can be used as both astructural support for this film layer if needed and as a thermalspreading and/or dispersion layer for the light sources. In someembodiments, the segments have film layers on both the first surface 36and the second surface 35.

FIG. 4 is schematic diagram front view of another illustrative backlightfor displaying alternating right and left images. This backlight 30 issimilar to the backlight described in FIG. 3A, however, this backlight30 has a single light source 32 or 34 providing light to a plurality ofsegments.

FIG. 5 is a schematic side elevation view of another illustrativebacklight for displaying alternating right and left images. This figureillustrates six segments 30 ₁, 30 ₂, 30 ₃, 30 ₄, 30 ₅, 30 ₆ that have acircular cross-sectional shape and includes a first curved surface 36 ₁,36 ₂, 36 ₃, 36 ₄, 36 ₅, 36 ₆ and an opposing second curved surface 35 ₁,35 ₂, 35 ₃, 35 ₄, 35 ₅, 35 ₆. The FIG. 5 segments are elongated lightrods. These elongated light rods have light extraction structures thatdirect the light out of the light transmission surface 35 ₁, 35 ₂, 35 ₃,35 ₄, 35 ₅, 35 ₆. Elongated light rods with extraction structures aredescribed in U.S. Pat. Nos. 5,432,876; 5,845,038; and 6,367,941.

With the advent of small, high brightness light sources such as LEDs,these light rods can be used for backlighting the LCD panels. Oneadvantage of these light sources, particularly LEDs, solid state lasersand OLEDs is the improved color gamut if red/green/blue and possiblyadditional colors such as white, cyan, magenta and yellow are used asthe illumination source. Having an array of spaced LEDs supplying thelight to the LCD panel has proven to provide sufficient illuminationlevels.

The light rod mimics the linear nature of fluorescent lamps by usingsolid state light sources with the linear light rod light guides.Commercially available LED packages, if bright enough, can simply becoupled into the linear light rods. For improved light injection, onemay use a tapered light rod at the injection point to capture the wideangle light and change the angles to allow total internal reflection(TIR) into and down the light rod. If additional light from each lightrod is needed or if one desires to incorporate red/green/blue as well asadditional colors, for example, white, cyan, magenta and yellow, intothe end of the light rod, one can use the features disclosed in U.S.Pat. No. 6,618,530, incorporated herein by reference, for combininglight sources into a single light guide end. Another way to increase theamount of light is to combine several LED die, possibly coated withphosphor(s) emitting at different and/or broader wavelengths in closeproximity to each other so that the overall light injected iscumulative. If allowed to space out the LED light sources along thelength of the light guide rod, one could provide additional light to thelinear light guide by periodically adding an LED injection site with theincorporation of a diverter into the side of the linear light rod.

One version of an elongated or linear light rod is the HL (highluminance) Light Fiber product (3M Company). Its construction is one ofcore and cladding. The core is an extremely clear acrylate surrounded bya fluoropolymer cladding. Additionally, the cladding is highly filledwith TiO₂ for enhanced extraction of light. Although it has the rightform factor, the extraction is around the whole diameter so additionalmaterials may be needed to reflect light that is not aimed at the LCDpanel. Another linear light guide could be the use of a clear PMMA rod.It is common to modify the rod shaped light guide with a stripe of whitepaint or other white material to extract light more aggressively in apreferred direction. One could vary the extraction rate down the lengthof the guide by changing the modification to the strip of material.Similarly, one could machine the stripe surface with extractionstructures to accomplish the light extraction. If those extractionstructures were engineered, optically smooth surfaces and close controlof the extracted light are possible. This method is disclosed in thefollowing US patents, all of which are incorporated herein by reference:U.S. Pat. Nos. 5,432,876; 5,845,038; and 6,367,941.

A tapered light guide for enhanced injection incorporates the angleprovided by the taper and uses it to change the angle of the exitinglight. The use of a harness coupler for having multiple LED injectioninto a given light guide is another method of transmitting multiple LEDlight into a linear light guide. The ability to pack many LED die into atight package is disclosed in US Patent Application No. 2005/0140270,incorporated herein by reference. This method allows for increasedbrightness by the addition of many die within the cross sectional areaof the rod shaped light guide. If the linear rod needs more light thanwhat can be provided into the ends, light can be injected periodicallyalong the length by using a type of diverter.

With the Light Fiber product (3M Company), one can get the linear rodform factor, but it may not be able to efficiently deliver light in acontrolled fashion to a specific target. Additional films or coatingsmay be required to redirect light that is not directed to the LCD panel.Another way to create a linear light guide is to modify an acrylic rod.By roughening the surface or adding a white stripe of material down thelength, one can extract light from the guide. Other ways include the useof a rectangular, light guide that employs optically smooth notches.This use for extracting light provides more efficient light extractionto the target and is disclosed in U.S. Pat. No. 5,894,539, incorporatedherein by reference. For improved angular control, while still using TIRfor extracting, one can use techniques disclosed in U.S. Pat. No.5,845,038, incorporated herein by reference. By adding additional rowsof notches, one can provide a wider cone of light, which helps provideuniform illumination to the back of the LCD panel. As shown in FIG. 5,the LED light rods can be used to form a scanning backlight assembly,which is controlled by an electronic system to deliver the scanningoperation. The backlight includes several spaced light rods illuminatedin sequence to provide the scanning function.

For all the described embodiments, each segment is lit with one or morelight sources in any useful configuration. In many embodiments, eachsegment is lit with a single LED, and each segment is sized such thatonly one LED can fit either the first or second side 31, 33.

Each segment first or second side has any useful length and a width, ordiameter value. In many embodiments, each segment first or second sidehas a length and a width, or diameter value of 2 millimeters or less. Inmany embodiments, each segment first or second side has a length and awidth, or diameter value in a range from 0.5 millimeters to 2millimeters. In some embodiments, each segment first or second side hasa length and a width, or diameter value of 5 millimeters or less.

The segments or channels can be formed in any useful manner. In manyembodiments, the segments or channels are formed by molding onto amaster tool or machining. Molding methods such as injection molding orcompression molding or web based microreplication may be used. If athinner light guide with fine pitch sections is desired, several of thelight guide sections may be joined together and illumined with a singlesource as shown in FIG. 4. Roll based fabrication processes may be usedand are more amenable to finer features (one millimeter or less) featuresizes. Larger features can be manufactured from flat tools by injectionmolding or compression molding. Combinations of finely structuredextractors or directional diffusers may also be laminated to courserlight guide channels or segments made by another process. It is alsopossible to use approaches similar to those for fiber opticilluminators. In addition to using prism extractor features, thecross-section of the segmented light guide may decrease as a function ofdistance from the light source, forming a converging wedge or taperedlight guide segment having the light source illuminating the wide sideof the converging wedge. Such converging wedge segments extract light athigh angles and may not need separate extraction features.

Thus, embodiments of the STEREOSCOPIC 3D LIQUID CRYSTAL DISPLAYAPPARATUS WITH SEGMENTED LIGHT GUIDE are disclosed. One skilled in theart will appreciate that the present invention can be practiced withembodiments other than those disclosed. The disclosed embodiments arepresented for purposes of illustration and not limitation, and thepresent invention is limited only by the claims that follow.

1. A backlight for a stereoscopic 3D liquid crystal display apparatus,comprising: a light guide formed from a plurality of segments, eachsegment having a first side and a second side opposite the first side,and having a first surface extending between the first and second sidesand a second surface opposite the first surface, wherein the firstsurface substantially re-directs light and the second surfacesubstantially transmits light, and the plurality of segments arearranged substantially in parallel with the second surfaces transmittinglight in substantially the same direction to provide backlighting for astereoscopic 3D liquid crystal display; a light source is disposed alongonly one of the first side or second side of each segment fortransmitting light into the light guide from either the first side orsecond side; wherein, each segment light source is selectively turned onand off in a particular pattern.
 2. A backlight for a stereoscopic 3Dliquid crystal display apparatus according to claim 1, wherein the lightsources are located on opposing first and second sides of each pair ofadjacent segments.
 3. A backlight for a stereoscopic 3D liquid crystaldisplay apparatus according to claim 1, wherein the segments include agraded extractor that provides substantially uniform extraction of lightfrom the second surface.
 4. A backlight for a stereoscopic 3D liquidcrystal display apparatus according to claim 1, wherein each lightsource comprises a one or more light emitting diodes.
 5. A backlight fora stereoscopic 3D liquid crystal display apparatus according to claim 1,wherein the segments have a converging wedge shape with the light sourcelocated at a wide side of the converging wedge.
 6. A backlight for astereoscopic 3D liquid crystal display apparatus according to claim 1,wherein each segment is partially separated from an adjacent segment byan air gap and each segment is joined with an adjacent segment at thefirst surface, or second surface, or between the first surface andsecond surface.
 7. A backlight for a stereoscopic 3D liquid crystaldisplay apparatus according to claim 1, wherein each segment iscompletely separated from an adjacent segment by an air gap.
 8. Abacklight for a stereoscopic 3D liquid crystal display apparatusaccording to claim 1, wherein each segment is completely separated froman adjacent segment.
 9. A backlight for a stereoscopic 3D liquid crystaldisplay apparatus according to claim 1, further comprising asynchronization driving element electrically coupled to the lightsources and the synchronization driving element synchronizes turningeach light source on or off in an alternating order between the firstand second sides.
 10. A backlight for a stereoscopic 3D liquid crystaldisplay apparatus according to claim 1, wherein the plurality ofsegments comprise elongated rods.
 11. A stereoscopic 3D liquid crystaldisplay apparatus, comprising: a liquid crystal display panel; driveelectronics configured to drive the liquid crystal display panel withalternating left eye and right eye images; and a backlight positioned toprovide light to the liquid crystal display panel, the backlightcomprising: a light guide formed from a plurality of segments, eachsegment having a first side and a second side opposite the first side,and having a first surface extending between the first and second sidesand a second surface opposite the first surface, wherein the firstsurface substantially re-directs light and the second surfacesubstantially transmits light, and the plurality of segments arearranged substantially in parallel with the second surfaces transmittinglight in substantially the same direction to provide backlighting for astereoscopic 3D liquid crystal display; a light source is disposed alongonly one of the first side or second side of each segment fortransmitting light into the light guide from either the first side orsecond side; wherein, each segment light source is selectively turned onand off in a particular pattern.
 12. A stereoscopic 3D liquid crystaldisplay apparatus according to claim 11, wherein the segments have aconverging wedge shape with the light source located at a wide side ofthe converging wedge.
 13. A stereoscopic 3D liquid crystal displayapparatus according to claim 11, wherein each light source selectivelytransmits light into the light guide based upon whether a right or leftimage is displayed on the liquid crystal display panel.
 14. Astereoscopic 3D liquid crystal display apparatus according to claim 11,wherein each light source is turned on or off in an alternating orderbetween the first and second sides and the light sources are located onopposing first and second sides of each pair of adjacent segments.
 15. Astereoscopic 3D liquid crystal display apparatus according to claim 11,further comprising a synchronization driving element electricallycoupled to the light sources and the synchronization driving elementsynchronizes turning each segment on or off in an alternating orderbetween the first and second sides.
 16. A stereoscopic 3D liquid crystaldisplay apparatus according to claim 11, wherein each segment ispartially separated from an adjacent segment by an air gap and the eachsegment is joined with an adjacent segment at the first planar surface,or second planar surface, or between the first planar surface and secondplanar surface.
 17. A stereoscopic 3D liquid crystal display apparatusaccording to claim 11, wherein each segment is completely separated froman adjacent segment.
 18. A stereoscopic 3D liquid crystal displayapparatus according to claim 11, wherein the plurality of segmentscomprise elongated rods.
 19. A stereoscopic 3D liquid crystal displayapparatus according to claim 11, wherein each light source comprises aone or more light emitting diodes.
 20. A stereoscopic 3D liquid crystaldisplay apparatus according to claim 11, wherein each segment first orsecond side has a length and a width, or diameter value of 2 millimetersor less.